The Cathedral Formation is a

stratigraphic unit A stratigraphic unit is a volume of rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features ( facies) that characteriz ...

in the southern

Canadian Rockies The Canadian Rockies () or Canadian Rocky Mountains, comprising both the Alberta Rockies and the British Columbian Rockies, is the Canadian segment of the North American Rocky Mountains. It is the easternmost part of the Canadian Cordillera, w ...

Alberta Alberta is a Provinces and territories of Canada, province in Canada. It is a part of Western Canada and is one of the three Canadian Prairies, prairie provinces. Alberta is bordered by British Columbia to its west, Saskatchewan to its east, t ...

and

British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...

, on the western edge of the

Western Canada Sedimentary Basin The Western Canada Sedimentary Basin (WCSB) underlies of Western Canada including southwestern Manitoba, southern Saskatchewan, Alberta, northeastern British Columbia and the southwest corner of the Northwest Territories. This vast sedimentary ba ...

. It is a thick sequence of

carbonate rock Carbonate rocks are a class of sedimentary rocks composed primarily of carbonate minerals. The two major types are limestone, which is composed of calcite or aragonite (different crystal forms of CaCO3), and Dolomite (rock), dolomite rock (also kn ...

s of

Middle Cambrian Middle or The Middle may refer to: * Centre (geometry), the point equally distant from the outer limits. Places * Middle (sheading), a subdivision of the Isle of Man * Middle Bay (disambiguation) * Middle Brook (disambiguation) * Middle Creek (di ...

age. It was named for Cathedral Mountain in

Yoho National Park Yoho National Park ( ) is a National Parks of Canada, national park of Canada. It is located within the Canadian Rockies, Rocky Mountains along the western slope of the Continental Divide of the Americas in southeastern British Columbia, bordere ...

Charles Doolittle Walcott Charles Doolittle Walcott (March 31, 1850February 9, 1927) was an American paleontologist, administrator of the Smithsonian Institution from 1907 to 1927, and director of the United States Geological Survey. He is famous for his discovery in 19 ...

, the discoverer of the

Burgess shale fossils The fossils of the Burgess Shale, like the Burgess Shale itself, are fossils that formed around 505 million years ago in the mid-Cambrian, Cambrian period. They were discovered in Canada in 1886, and Charles Doolittle Walcott collected over 65,0 ...

. The Cathedral Formation includes fossil

stromatolites Stromatolites ( ) or stromatoliths () are layered sedimentary formations ( microbialite) that are created mainly by photosynthetic microorganisms such as cyanobacteria, sulfate-reducing bacteria, and Pseudomonadota (formerly proteobacteria) ...

oncolite Oncolites are sedimentary structures composed of oncoids, which are layered structures formed by the growth of one or more species of microorganisms, usually containing cyanobacteria. Oncolites are very similar to stromatolites, but, instead of ...

s, and other

algal Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular microalgae, s ...

remains, as well as a few

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny f ...

beds with

trilobite Trilobites (; meaning "three-lobed entities") are extinction, extinct marine arthropods that form the class (biology), class Trilobita. One of the earliest groups of arthropods to appear in the fossil record, trilobites were among the most succ ...

s. The Cathedral escarpment on its westernmost edge is thought to have played a major role in the deposition and preservation of the Burgess shale fossils.

Lithology and deposition

The Cathedral Formation consists primarily of massive, cliff-forming

s. It was originally deposited as

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

, much of which may have been secreted by marine

algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

. Deposition took place in shallow water on an extensive algal reef or

carbonate platform A carbonate platform is a Sedimentary rock, sedimentary body which possesses topographic relief, and is composed of Autochthon (geology), autochthonic calcareous deposits. Platform growth is mediated by Sessility (zoology), sessile organisms whose ...

that had developed along the western margin of the

North American Craton North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating direction or geography. Etymology The word ''north'' ...

.Conway Morris, S. and Whittington, H.B. 1985. Fossils of the Burgess Shale, a national treasure in Yoho National Park, British Columbia. Geological Survey of Canada, Miscellaneous Report 43, 31 p.Aitken, J.D. 1997. Stratigraphy of the Middle Cambrian platformal succession, southern Rocky Mountains. Geological Survey of Canada, Bulletin 398, 322 p. The limestone was subsequently altered to dolomite in many areas. The formation also includes several beds of shale with fossil trilobites that establish its age and stratigraphic relationships by

biostratigraphy Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them.Hine, Robert. "Biostratigraphy." ''Oxford Reference: Dictionary of Biology ...

Cathedral escarpment

The Cathedral escarpment is an abrupt cliff on the westernmost edge of the Cathedral Formation. It was probably a submarine cliff that marked the edge of the original carbonate platform. It is approximately 100 to 300 metres (330 to 1000 feet) high and extends for about 100 kilometres (62 miles) running through and around

, although only small portions of it are exposed. During the deposition of the

Stephen Formation The Stephen Formation is a geologic formation exposed in the Canadian Rockies of British Columbia and Alberta, on the western edge of the Western Canada Sedimentary Basin. It consists of shale, thin-bedded limestone, and siltstone that was deposit ...

, mudflows ran down and along the escarpment, trapping the Burgess shale organisms and burying them quickly at the base of the cliff. This prevented their decay, preserving their soft tissues as well as their hard parts in the Stephen Formation shales.

Distribution and stratigraphic relationships

The Cathedral Formation is present in the southern Canadian Rockies of southwestern Alberta and southeastern British Columbia. It reaches a maximum thickness of about 610 metres (2000 feet) at

Mount Stephen Mount Stephen, , is a mountain located in the Kicking Horse River Valley of Yoho National Park, km east of Field, British Columbia, Field, British Columbia, Canada. The mountain was named in 1886 for George Stephen, 1st Baron Mount Stephen, Geo ...

. It is in gradational contact with the underlying Mount Whyte and Naiset Formations, and with the overlying

. To the west, the Cathedral Formation terminates abruptly against the shales of the Stephen Formation at the Cathedral escarpment. The formation thins eastward, grading into the

Earlie Formation The Earlie Formation is a stratigraphic unit of Middle Cambrian age in the Western Canada Sedimentary Basin that is present beneath the plains of Alberta and eastern Saskatchewan. It was named for Earlie Lake in the County of Vermilion River, Al ...

beneath the Alberta plains. To the north it grades into the Snake Indian Formation. It is equivalent to the thinner Elko Formation to the south.

Economic resources

The Cathedral Formation hosts deposits of

magnesite Magnesite is a mineral with the chemical formula ( magnesium carbonate). Iron, manganese, cobalt, and nickel may occur as admixtures, but only in small amounts. Occurrence Magnesite occurs as veins in and an alteration product of ultramafic r ...

(MgCO₃) at Mt. Brussilof, about 35 km (22 miles) northwest of

Radium Hot Springs Radium Springs may refer to: __NOTOC__ Canada *Radium Hot Springs, British Columbia, a village in British Columbia ** Radium Hot Springs Airport United States *Radium Springs, Georgia *Radium Springs, New Mexico *Radium Hot Springs (Colorado), ...

in British Columbia. The

ore Ore is natural rock or sediment that contains one or more valuable minerals, typically including metals, concentrated above background levels, and that is economically viable to mine and process. The grade of ore refers to the concentration ...

consists of magnesite-rich sparry

carbonate A carbonate is a salt of carbonic acid, (), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word "carbonate" may also refer to a carbonate ester, an organic compound containing the carbonate group ...

masses that have been mined by

open-pit Open-pit mining, also known as open-cast or open-cut mining and in larger contexts mega-mining, is a surface mining technique that extracts rock (geology), rock or minerals from the earth. Open-pit mines are used when deposits of commercially ...

methods since 1982. The ore is processed to produce

magnesium oxide Magnesium oxide (MgO), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions ...

(MgO) at

Exshaw, Alberta Exshaw is a hamlet in Alberta, Canada, within Municipal District (MD) of Bighorn No. 8. Located approximately west of downtown Calgary and east of Canmore, Exshaw is situated within the Bow River valley north of the Bow River. The hamlet ...

. The formation also hosts deposits of

lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...

zinc Zinc is a chemical element; it has symbol Zn and atomic number 30. It is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic tabl ...

, and

silver Silver is a chemical element; it has Symbol (chemistry), symbol Ag () and atomic number 47. A soft, whitish-gray, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. ...

in the

Kicking Horse Pass Kicking Horse Pass (el. ) is a high mountain pass across the Continental Divide of the Americas of the Canadian Rockies on the Alberta–British Columbia border, and lying within Yoho and Banff national parks. Divide Creek forks onto both ...

east of

Field, British Columbia Field is an unincorporated community of approximately 169 people located in the Kicking Horse River valley of southeastern British Columbia, Canada, within the confines of Yoho National Park. At an elevation of , it is west of Lake Louise a ...

. They were discovered in 1884 during the construction of the

Canadian Pacific Railway The Canadian Pacific Railway () , also known simply as CPR or Canadian Pacific and formerly as CP Rail (1968–1996), is a Canadian Class I railway incorporated in 1881. The railway is owned by Canadian Pacific Kansas City, Canadian Pacific Ka ...

, and are Mississippi Valley-Type (MVT) deposits. They were mined intermittently for more than 60 years.Ney, C.S. 1954. Monarch and Kicking Horse mines, Field, British Columbia. Guide book, 4th Annual Field Conference Banff-Golden-Radium. Canadian Society of Petroleum Geologists. The primary ore

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...

s are

pyrite The mineral pyrite ( ), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Fe S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic luster and pale brass-yellow hue ...

sphalerite Sphalerite is a sulfide mineral with the chemical formula . It is the most important ore of zinc. Sphalerite is found in a variety of deposit types, but it is primarily in Sedimentary exhalative deposits, sedimentary exhalative, Carbonate-hoste ...

, and

galena Galena, also called lead glance, is the natural mineral form of lead(II) sulfide (PbS). It is the most important ore of lead and an important source of silver. Galena is one of the most abundant and widely distributed sulfide minerals. It crysta ...

, which are associated with dolomite, minor

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

, and

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

. The abandoned mine portals and

adit An adit (from Latin ''aditus'', entrance) or stulm is a horizontal or nearly horizontal passage to an underground mine. Miners can use adits for access, drainage, ventilation, and extracting minerals at the lowest convenient level. Adits are a ...

s can still be seen along the cliffs that flank the

Transcanada Highway The Trans-Canada Highway ( French: ; abbreviated as the TCH or T-Can) is a transcontinental federal–provincial highway system that travels through all ten provinces of Canada, from the Pacific Ocean on the west coast to the Atlantic Ocean on ...

.Leckie, D.A. 2017. Rocks, ridges and rivers – Geological wonders of Banff, Yoho, and Jasper National Parks. Brokenpoplars, Calgary, Alberta, 217 pp. .

References

{{Western Canadian Sedimentary Basin, Canadian Rockies=yes Cambrian Alberta Cambrian System of North America Geologic formations of Alberta Geologic formations of British Columbia Burgess Shale Cambrian British Columbia Western Canadian Sedimentary Basin Yoho National Park Limestone formations of Canada Dolomite formations of Canada Mudstone formations of Canada